| Time-Resolved MR
Angiography: Artery-Vein Separation using Correlation Analysis Michael
Bock, Deutsches Krebsforschungszentrum (dkfz), Heidelberg, Germany
With modern magnetic resonance (MR) scanners time-resolved
3D data sets of the blood vessels (MR angiographies) can be acquired in a single breath
hold period. The series of 3D data sets shows the transit of contrast media (e.g. Gd-DTPA)
through the vasculature and, thus, contains more information than static angiographies
alone. In the lung, this dynamic information can e.g. be utilised to separate arterial
from venous blood vessels. Since contrast media transit times through the lung can be very
short, the individual 3D data sets often show signals from both arterial and venous
vessels.

MR angiography post-processing tool
ANALYSE_4D
At the Deutsches Krebsforschungszentrum (German Cancer Research Center, DKFZ) the
research group of Michael Bock has implemented an IDL tool, ANALYZE_4D, to post-process 4D
MR angiography data sets. With this tool pure arterial and venous MR angiographies are
computed from the many hundred original image files. To separate arteries from veins, a
modified correlation analysis approach is used. After selection of a reference arterial or
venous vessel the correlation analysis emphasizes only those vessel structures that show a
similar enhancement pattern.

Result of an artery-vein separation:
lung arteries (blue) and veins (red) were separated by their distinctive contrast
enhancement patterns.
For this project, the researchers at the
DKFZ have chosen IDL as a development platform for various reasons:
- The integrated DICOM support facilitates vendor-independent handling of the MR images.
- The IDL virtual machine allows to disseminate the program to the clinical end users at
the DKFZ with no additional cost for licenses.
- The program can be used on a variety of host computers due to IDL's platform
independence.
- The graphics capabilities as well as the programmer-friendly GUI capabilites make IDL an
excellent environment to develop both research-oriented and user-friendly applications.
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